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The metal-insulator interface of hydrogen-sensitive metal-insulator-semiconductor capacitors, with SiO2 as the insulator and Pt as the metal contact, was discussed. It was found that the difference in hydrogen response between differently prepared devices was explained by a difference in concentration of available adsorption sites. The analysis showed that the concentration of Pt atoms in contact with the oxide affected both the hydrogen response and the metal-oxide adhesion.

This pilot study evaluates the clinical stability of bisphosphonate-coated dental implants placed using a two-stage surgical procedure in five patients. Each patient received seven regular Branemark implants, one of which was coated with bisphosphonate in a fibrinogen matrix. The coated implant was inserted where the bone was expected to have the least favourable quality. The level of the marginal bone around each implant was measured by intraoral periapical radiographs and implant stability was recorded using resonance frequency measurements. Frequency values (ISQ) were obtained peroperatively before flap closure and after 6 months at abutment connection. At abutment connection the bisphosphonate-coated implants were removed en bloc in two patients for histological examination. An animal experiment had previously confirmed that gamma-sterilization did not reduce bioactivity of the bisphosphonate coating. In each patient, the bisphosphonate-coated implant showed the largest improvement in ISQ level of all implants. Their values at the start tended to be lower, and the absolute value at 6 months did not differ. No complications occurred with the coated implants. Histology showed no abnormalities. Improvement in ISQ values was an expected effect of the bisphosphonate coating, but could be due to the choice of insertion site. This finding warrants a randomized blinded study.

Hydrogen-sensitive palladium-gate MOS structures heated above 150°C show sensitivity to ethanol vapor. The effect is probably due to catalytic dehydrogenation of adsorbed ethanol molecules on the surface of the palladium gate.

This communication reports the first steps in the construction of a novel, nanoparticle-based hybrid material for biomimetic and biosensor applications. Gold nanoparticles were modified with synthetic polypeptides to enable control of the particle aggregation state in a switchable manner, and particle aggregation was, in turn, found to induce folding of the immobilized peptides.

The spectral fingerprinting of the excitation emission matrix (EEM) of fluorescent substances is demonstrated using polychromatic light sources and tri-chromatic image detectors. A model of the measured fingerprints explaining their features and classification performance, based on the polychromatic excitation of the indicators is proposed.

Substantial amount of spectral information is retained in the fingerprints as corroborated by multivariate analysis and experimental conditions that favor such situation are identified.

In average, for five different substances, the model shows a fitting goodness measured by the Pearsons r coefficient and the root mean square deviation of 0.8541 and 0.0247 respectively, while principal component classification patterns satisfactorily compare with the EEM spectroscopy classification and respectively explain 96% and 93% of the information in the fist two principal components.

The measurements can be performed using regular computer screens as illumination and web cameras as detectors, which constitute ubiquitous and affordable platforms compatible with distributed evaluations, in contrast to regular instrumentation for EEM measurements.

Hydrogen permeation through a 25-µm thick palladium membrane during continuous exposures of hydrogen together with different combinations of oxygen and carbon monoxide has been studied at membrane temperatures of 100 °C-250 °C (total pressures of 40-150 Torr). Both CO and O2, individually, inhibit hydrogen permeation through the membrane. The cause of the inhibition is, however, somewhat different. CO blocks available hydrogen dissociation sites, while oxygen both blocks dissociation sites and also consumes adsorbed hydrogen through the production of water. When a combination of CO and O2 is supplied together with hydrogen, new reaction pathways will emerge. The carbon dioxide formation will dominate the water forming reaction, and consequently, the blocking effect caused by the formation of water will be suppressed. In a mixture of CO+O2+H2, the hydrogen permeation can become either larger or smaller than that due to only O2+H2 or CO+H2 depending on the CO/O2 ratio. It is thus possible to find a situation where carbon monoxide and oxygen react to form CO2 leaving adsorbed hydrogen free to permeate the membrane.

The dehydrogenation of ethanol and the subsequent permeation were studied on a Pd membrane in a continuous ethanol supply. Hydrogen could not be extracted as efficiently from ethanol as from methanol. In ethanol, at least four of the six hydrogen atoms were not available for permeation because of methane formation. Hydrogens bonded to a carbon atom in a C-O group were available for permeation, while hydrogen atoms bonded to a carbon atom without oxygen were not. The efficiency of hydrogen permeation from ethanol was 5% compared to that of pure hydrogen, which could be compared to 25% for methanol compared to pure hydrogen. The hydrogen permeation could be enhanced by adding CO to the EtOH + O2 supply. The permeation probability of the hydrogen bonded to the methylene hydrogen increased while the water formation with this hydrogen atom decreased. Acetic acid was formed upstream when oxygen was in excess. The differently bonded hydrogen atoms in an ethanol molecule experienced different reaction pathways. The results did not contradict the models made from surface experiments in ultrahigh vacuum by Davis and Barteau, Holroyd and Bowker, or Bowker et al.

The dehydrogenation of methanol and the subsequent permeation of hydrogen through a 25 μm thick palladium film has been studied in a catalytic membrane reactor. At the temperature studied, 350°C, the decomposition pathway for methanol on clean palladium surfaces is believed to lead to Had and a carbonaceous overlayer. The released hydrogen can either desorb or permeate the palladium membrane. During a continuous supply of methanol hydrogen permeation is reduced and, eventually, totally quenched by the growing carbon monoxide/carbon coverage. Adding oxygen in the methanol supply can balance the increasing carbonaceous coverage through the production of carbon dioxide. In such a case, it is concluded that no CO bond scission occurs. The methanol/oxygen ratio is crucial for the hydrogen permeation rate. Isotope-labelled methanol, CH3OH, CH3OD, CD3OH and CD3OD, shows that it is preferentially the methyl (or methoxy) hydrogen that permeates the membrane.

We have demonstrated a general way to tune the emission of poly(alkylthiophenes) by using steric interaction between the repeating units. Light-emitting diodes prepared of the polymers have blue to near-infrared emission.

We report a systematic approach to the control of the conjugation length along the poly(thiophene) backbone. The planarity of the main chain can be permanently modified by altering the pattern of substitution and character of the substituents on the poly(thiophene) chain, and the conjugation length is thus modified. We obtain blue, green, orange, red, and near-infrared electroluminescence from four chemically distinct poly(thiophenes). The external quantum efficiencies are in the range of 0.01-0.6%.

Increasing oil prices and environmental levies have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets in water based heating systems. The combustion process itself proceeds through three elementarysteps; drying, where fuel moisture is driven off, followed by pyrolysis and finally combustion of the remaining charcoal. Given the sufficient amount of air, good mixing and long enough residence time at elevated temperatures, the short-chained hydrocarbons and carbon monoxide formed during pyrolysis andchar combustion will burn to completion leaving only CO2 and H2O in the flue gases.

In case of air deficiency, combustion will be incomplete, leaving noxious compounds, like certain hydrocarbons and CO, behind. Too much of excess air, on the other hand, will lower the temperature of the combustion chamber, giving rise to both emissions of unburned material and, due to the forcedconvection of heat out the chimney, an impaired boiler efficiency. The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the airflows during combustion. The amount of air needed for complete oxidation of the fuel varies with the phase of combustion, fuel, fuel quality and load, however, why an active control of the airflows is considered a prerequisite. So far, nocontrol schemes have been applied to small- and medium-sized combustors, though, mainly dependent on the lack of cheap and simple means to measure basic flue gas parameters, like oxygen, hydrocarbons and CO.

Here is reported about the possible use of a system comprising SiC based field effect sensors to monitor the state of combustion, applicable to domestic heating systems, where only a rough picture of the air to fuel relationship is needed. Furthermore, it has been shown possible to obtain a multivariate linear regression model for propene (a model hydrocarbon) by the application of an array of SiC field effect sensors in a varying background of typical flue gas constituents, as long as thevariation is not too large. This model could possibly be applied to a control scheme for medium sized boilers, where smaller variations of flue gas constituents are encountered, and the possibility of simultaneous ammonia estimations has also opened up the field of flue gas after-treatment controlapplications, monitoring ammonia slip from selective noncatalytic reduction of nitrogen oxides by ammonia. The quantitative estimation of hydrocarbons over a wider range of concentrations and backgrounds, as well as of minor flue gasspecies, NO and CO, is however not possible with the SiC sensors currently comprising the sensor system.

Abstract [en]

Different catalytic materials, like Pt and Ir, applied as gate contacts on metal insulator silicon carbide field effect transistors — MISiCFET—facilitate the manufacture of gas sensor devices with differences in selectivity, devices which due to the chemical stability and wide band gap of SiC are suitable for high temperature applications. The combination of such devices in a sensor system, utilizing multivariate analysis/modeling, have been tested and some promising results in respect of monitoring a few typical exhaust and flue gas constituents, in the future aiming at on board diagnostics (OBD) and combustion control, have been obtained.

Abstract [en]

The possible utility of MISiCFET gas sensors in the application of combustion control in small-scale boilers has been tested and compared to commercially available resistive-type MOS sensors. The results suggest that by using the signals from one or more MISiCFET sensors, together with the measured temperature of the furnace, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

Increasing oil prices and concerns about global warming have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets. Combustion at non-optimal conditions can, however, lead to substantial emissions of noxious compounds like unburned hydrocarbons, carbon monoxide, and nitrogen oxides as well as the generation of soot.

Depending on the rate of combustion more or less air is needed per unit time to completely oxidize the fuel; deficiency of air leading to emissions of unburned matter and too much of excess air to slow combustion kinetics and emissions of mainly carbon monoxide. The rate of combustion is influenced by parameters like fuel quality – moisture and ash content etc. – and in what phase the combustion takes place (in the gas phase through combustion of evaporated substances or on the surface of char coal particles), none of which is constant over time.

The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the air supply throughout the combustion process. So far, no control schemes have been applied to small-scale combustors, though, mainly due to the lack of cheap and simple means to measure basic flue gas parameters like oxygen, total hydrocarbon, and carbon monoxide concentrations.

This thesis reports about investigations on and characterization of silicon carbide (SiC) based Metal Insulator Semiconductor (MIS) field effect gas sensors regarding their utility in emissions monitoring and combustion control applications as well as the final development of a sensor based control system for wood fired domestic heating systems.

From the main sensitivity profiles of such sensor devices, with platinum (Pt) and iridium (Ir) as the catalytic metal contacts (providing the gas sensing ability), towards some typical flue gas constituents as well as ammonia (NH3), a system comprising four individual sensors operated at different temperatures was developed, which through the application of Partial Least Squares (PLS) regression, showed good performance regarding simultaneous monitoring of propene (a model hydrocarbon) and ammonia concentrations in synthetic flue gases of varying content. The sensitivity to CO was, however, negligible. The sensor system also performed well regarding ammonia slip monitoring when tested in real flue gases in a 5.6 MW boiler running SNCR (Selective Non-Catalytic reduction of nitrogen oxides with ammonia).

When applied to a 200 kW wood pellet fuelled boiler a similar sensor system was, however, not able to follow the flue gas hydrocarbon concentration in all encountered situations. A PCA (Principal Components Analysis) based scheme for the manipulation of sensor and flue gas temperature data, enabling monitoring of the state of combustion (deficiency or too much of excess air), was however possible to develop. The discrepancy between laboratory and field test results was suspected and later on shown to depend on the larger variation in CO and oxygen concentrations in the flue gases as compared to the laboratory tests.

Detailed studies of the CO response characteristics for Pt gate MISiC sensors revealed a highly non-linear sensitivity towards CO, a large response only encountered at high CO/O2 ratios or low temperatures. The response exhibits a sharp switch between a small and a large value when crossing a certain CO/O2 ratio at constant operating temperature, correlated to the transition from an oxygen dominated to an almost fully CO covered Pt surface, originating from the difference in adsorption kinetics between CO and O2. Indications were also given pointing towards an increased sensitivity to background hydrogen as being the mediator of at least part of the CO response. Some general characteristics regarding the response mechanism of field effect sensors with differently structured metal contacts were also indicated.

The CO response mechanism of Pt metal MISiC sensors could also be utilized in developing a combustion control system based on two sensors and a thermocouple, which when tested in a 40 kW wood fired boiler exhibited a good performance for fuels with extremely low to normal moisture content, substantially decreasing emissions of unburned matter.

Abstract [en]

Different catalytic materials, like Pt and Ir, applied as gate contacts on metal insulator silicon carbide field effect transistors — MISiCFET—facilitate the manufacture of gas sensor devices with differences in selectivity, devices which due to the chemical stability and wide band gap of SiC are suitable for high temperature applications. The combination of such devices in a sensor system, utilizing multivariate analysis/modeling, have been tested and some promising results in respect of monitoring a few typical exhaust and flue gas constituents, in the future aiming at on board diagnostics (OBD) and combustion control, have been obtained.

Lloyd Spetz, Anita

Mattsson, Mattias

Vattenfall Utveckling AB, Älvkarleby, Sweden.

Ljung, Per

Vattenfall Utveckling AB, Älvkarleby, Sweden.

2007 (English)Manuscript (preprint) (Other academic)

Abstract [en]

Gas sensitive Metal Insulator Silicon Carbide Field Effect Transistor – MISiCFET – devices have shown good possibilities of realizing sensors for high temperature applications. One such application could be the monitoring of ammonia slip from boilers running SNCR – Selective Non-Catalytic Reduction of nitrogen oxides (NOx) with ammonia (NH3). In this study a number of MISiCFET gas sensors operated at different temperatures and with both platinum (Pt) and iridium (Ir) as the gate contact have been tested for their ability to detect and quantify ammonia slip in flue gases from a 5.6 MW wood fired boiler during a test of a new SNCR-system. The individual sensors have been evaluated and compared to each other for the sensitivity towards NH3 and possible cross-sensitivities to other flue gas species through the comparison of the sensor signals with the signals from analytical instruments like FTIR – Fourier Transform Infrared spectroscopy – for nitrogen oxides (NO + NO2), NH3, and carbon monoxide (CO) and an FID – Flame Ionization Detector – for the Total Hydrocarbon Concentration (THC). The ability of a combination of sensors to provide extra or more accurate information about the NH3 concentration was also evaluated through the construction and validation of a Partial Least Squares – PLS – regression model based on all the sensor signals. Under the assumption that the sensors’ responses follow a logarithmic dependence on NH3 concentration the results regarding ammonia slip quantification were promising both for a single Ir sensor and for the system based on all sensors. There is still a question mark for the long-term stability of the devices in real flue gases, however.

Abstract [en]

SiC based field effect gas sensors have been evaluated for future possible use in combustion control schemes for domestic heating systems. Emphasis has been on the possibility to monitor the state of combustion and follow the development of the combustion process from an emissions point of view and to determine its cause. The sensor signals have been compared to true emissions data – CO and total hydrocarbon concentration – as obtained by an IR spectrometer and a flame ionization detector (FID) as well as flue gas concentration of oxygen as obtained by a paramagnetic cell. The sensor characteristics have been evaluated using multivariate statistics and the results suggest that, by using the signals from one or more SiC-based field effect sensors and a thermocouple, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

Lloyd Spetz, Anita

Abstract [en]

The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards carbon monoxide (CO) at varying oxygen (O2) concentrations and over a wide range of temperatures have been investigated in detail at atmospheric pressure. The influence of hydrogen (H2) on the CO response was also studied. Sensor devices with thin, porous as well as dense, homogeneous Pt films on top of both silicon dioxide (SiO2) and magnesium oxide (MgO) as insulator materials were investigated in this study. The reaction products generated on the sensor surfaces were also monitored with a mass spectrometer connected to the gas flow just downstream of the sensor location and the results compared to CO oxidation characteristics over Pt/SiO2 and to some extent Pt/MgO catalysts as reported in literature. By correlating the response characteristics of these devices with CO2 formation and hydrogen consumption on the sensor surfaces, strong indications for a CO response mechanism involving a CO induced increased sensitivity to background hydrogen have been obtained, this mechanism being hypothesized to be the only one behind the CO sensitivity of devices with dense Pt metal contacts. The results also give further support to the idea that also other processes than an increased sensitivity to background hydrogen contribute to the CO response of sensor devices with a porous platinum film as the metal contact, one candidate being the removal of oxygen anions from the surface of exposed oxide areas through the oxidation reaction with CO.

National Category

Physical Sciences

Identifiers

urn:nbn:se:liu:diva-13095 (URN)

Note

This manuscript was never submitted to a journal and will not be published.

Lloyd Spetz, Anita

Abstract [en]

The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards nitrogen oxide (NO) for both low as well as relatively high background oxygen (O2) concentrations and different temperatures have been investigated at atmospheric pressure. Devices with both porous and dense Pt metal gate contacts have been investigated and the results seem to confirm the theories and results from earlier measurements regarding the requirement of porous metal films for the existence of a response to NO for this kind of sensor device. The results also suggest that no NO induced increased sensitivity to background hydrogen exists, at least it does not play any role in the observed NO sensitivity, as opposed to what has been suggested in the case of CO. The obtained results are also discussed in relation to some of the proposed sensing mechanisms for non-hydrogen containing substances and in comparison to NO reduction characteristics on Pt/SiO2 catalysts, as reported in literature. The results further give some indications about also some other process/ processes being important for the response of SiC based field effect sensors towards NO than just adsorption/desorption.

National Category

Physical Sciences

Identifiers

urn:nbn:se:liu:diva-13096 (URN)

Note

This manuscript was never submitted to a journal and will not be published.

The temperature dependence of the sensor response towards CO of SiC-FET sensors has been studied by combining in situ DRIFT spectroscopy and sensor response measurements. The DRIFT spectroscopy studies have been performed on a model sensor representing the top layer of a SiC-FET sensor with porous Pt gate. Adsorbates on the model sensor have been studied at varying temperatures and gas concentrations, and correlated to sensor response measurements at similar experimental conditions. The results show that the temperature dependence partly can be correlated to the CO coverage of the surface. The switching point of the sensor response, observed at different temperatures depending on the CO and oxygen concentrations is well in accordance with the kinetics of the CO oxidation reaction.

The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards carbon monoxide (CO) at varying oxygen (O2) concentrations and over a wide range of temperatures have been investigated in detail at atmospheric pressure. The influence of hydrogen (H2) on the CO response was also studied. Sensor devices with thin, porous as well as dense, homogeneous Pt films on top of both silicon dioxide (SiO2) and magnesium oxide (MgO) as insulator materials were investigated in this study. The reaction products generated on the sensor surfaces were also monitored with a mass spectrometer connected to the gas flow just downstream of the sensor location and the results compared to CO oxidation characteristics over Pt/SiO2 and to some extent Pt/MgO catalysts as reported in literature. By correlating the response characteristics of these devices with CO2 formation and hydrogen consumption on the sensor surfaces, strong indications for a CO response mechanism involving a CO induced increased sensitivity to background hydrogen have been obtained, this mechanism being hypothesized to be the only one behind the CO sensitivity of devices with dense Pt metal contacts. The results also give further support to the idea that also other processes than an increased sensitivity to background hydrogen contribute to the CO response of sensor devices with a porous platinum film as the metal contact, one candidate being the removal of oxygen anions from the surface of exposed oxide areas through the oxidation reaction with CO.

The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards nitrogen oxide (NO) for both low as well as relatively high background oxygen (O2) concentrations and different temperatures have been investigated at atmospheric pressure. Devices with both porous and dense Pt metal gate contacts have been investigated and the results seem to confirm the theories and results from earlier measurements regarding the requirement of porous metal films for the existence of a response to NO for this kind of sensor device. The results also suggest that no NO induced increased sensitivity to background hydrogen exists, at least it does not play any role in the observed NO sensitivity, as opposed to what has been suggested in the case of CO. The obtained results are also discussed in relation to some of the proposed sensing mechanisms for non-hydrogen containing substances and in comparison to NO reduction characteristics on Pt/SiO2 catalysts, as reported in literature. The results further give some indications about also some other process/ processes being important for the response of SiC based field effect sensors towards NO than just adsorption/desorption.

Different catalytic materials, like Pt and Ir, applied as gate contacts on metal insulator silicon carbide field effect transistors — MISiCFET—facilitate the manufacture of gas sensor devices with differences in selectivity, devices which due to the chemical stability and wide band gap of SiC are suitable for high temperature applications. The combination of such devices in a sensor system, utilizing multivariate analysis/modeling, have been tested and some promising results in respect of monitoring a few typical exhaust and flue gas constituents, in the future aiming at on board diagnostics (OBD) and combustion control, have been obtained.

An investigation of the influence and role of oxygen in the detection of non-hydrogen containing substances with Pt/SiO2/SiC based MOS field effect sensors, employing new model systems, has been carried out. With the use of a novel intermediate layer, by which the direct influence of hydrogen on the sensor response can be markedly reduced, the part of the sensor response which is not directly related to hydrogen (which to a small extent is always present in any gas mixture) could be resolved. The Pt/SiO2 NO reduction/oxidation model system has also been studied from a sensor perspective and the results compared to spectroscopic and mass spectrometry studies of the surface reactions from the field of catalysis. The results support the hypothesis from earlier work that the removal of oxygen from the sensor surface (e.g. by oxidation reactions with CO or NO) to a certain extent directly is involved in the detection of non-hydrogen containing species.

To gain knowledge about the transduction mechanisms involved in the sensitivity of field effect gas sensors towards non-hydrogen containing substances, such as O-2, NO and CO, the sensor signal characteristics during exposure of some conceptually different model sensors to these as well as hydrogen containing gases have been investigated. The MOS capacitor based model sensors employ different combinations of insulator and contact materials, such as MgO, LaF3, IrO2 etc. The gas composition downstream of the sensor during test gas exposure at various conditions has also been studied by mass spectrometry (MS) and compared for the different model systems. The results have been compared to the characteristics of ordinary SiC/SiO2/Pt structures and from the information obtained a tailor made field effect sensor structure for oxygen sensing, to our knowledge for the first time with minimal interference from H-2, CO, and hydrocarbons, has been tested with promising results.

Gas sensitive Metal Insulator Silicon Carbide Field Effect Transistor – MISiCFET – devices have shown good possibilities of realizing sensors for high temperature applications. One such application could be the monitoring of ammonia slip from boilers running SNCR – Selective Non-Catalytic Reduction of nitrogen oxides (NOx) with ammonia (NH3). In this study a number of MISiCFET gas sensors operated at different temperatures and with both platinum (Pt) and iridium (Ir) as the gate contact have been tested for their ability to detect and quantify ammonia slip in flue gases from a 5.6 MW wood fired boiler during a test of a new SNCR-system. The individual sensors have been evaluated and compared to each other for the sensitivity towards NH3 and possible cross-sensitivities to other flue gas species through the comparison of the sensor signals with the signals from analytical instruments like FTIR – Fourier Transform Infrared spectroscopy – for nitrogen oxides (NO + NO2), NH3, and carbon monoxide (CO) and an FID – Flame Ionization Detector – for the Total Hydrocarbon Concentration (THC). The ability of a combination of sensors to provide extra or more accurate information about the NH3 concentration was also evaluated through the construction and validation of a Partial Least Squares – PLS – regression model based on all the sensor signals. Under the assumption that the sensors’ responses follow a logarithmic dependence on NH3 concentration the results regarding ammonia slip quantification were promising both for a single Ir sensor and for the system based on all sensors. There is still a question mark for the long-term stability of the devices in real flue gases, however.

SiC based field effect gas sensors have been evaluated for future possible use in combustion control schemes for domestic heating systems. Emphasis has been on the possibility to monitor the state of combustion and follow the development of the combustion process from an emissions point of view and to determine its cause. The sensor signals have been compared to true emissions data – CO and total hydrocarbon concentration – as obtained by an IR spectrometer and a flame ionization detector (FID) as well as flue gas concentration of oxygen as obtained by a paramagnetic cell. The sensor characteristics have been evaluated using multivariate statistics and the results suggest that, by using the signals from one or more SiC-based field effect sensors and a thermocouple, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

The possible utility of MISiCFET gas sensors in the application of combustion control in small-scale boilers has been tested and compared to commercially available resistive-type MOS sensors. The results suggest that by using the signals from one or more MISiCFET sensors, together with the measured temperature of the furnace, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

Imaging surface plasmon resonance (iSPR) was used in conjunction with voltammetry to investigate the possibility of detecting local electrochemical processes in situ on chemically modified electrodes. More specifically, a pattern of self-assembled monolayers (SAMs) of thiocholesterol and 1-hexadecanethiol was microcontact printed on gold substrates, and the blocking characteristics on different parts of the pattern were investigated. The SPR images reflected the changes in the refractive index over the working electrode due to electrochemical processes, which in the present case showed the ability of the SAMs to impede faradaic reactions. The results show that differences in packing densities or porosity of SAMs in different regions of a patterned surface can be visualized as electrochemical images using iSPR. The strength of utilizing an optical detection method for electrochemical characterization lies in the ability to achieve lateral resolution in real-time. Electrochemical reactions can also be used to enhance the contrast in SPR images of thin layers of components with similar thicknesses and refractive indices.